U.S. Secretary of Defense Jim Mattis, accompanied by Joint Chiefs of Staff Chairman Gen. Joseph Dunford, made a surprise visit to Afghanistan on Friday for meetings with President Ashraf Ghani to discuss security issues and the prospect of peace talks with the Taliban.

The future U.S. fight against terrorists will be to train and advise partner militaries to take them on and prevent them from establishing safe havens in their countries, according to top U.S. officials.

Chairman of the Joint Chiefs of Staff Marine Gen. Joseph Dunford cautioned against talk of “World War III” after a U.S. military plane shot down a Syrian regime fighter jet over the skies of Syria on Sunday.

The highest-ranking military officer in the U.S. confirmed that the Islamic State (ISIS/ISIL) used a potentially deadly “sulfur-mustard blister agent” to target a base in northern Iraq that houses American troops. This marks the first recorded chemical attack on the United States since the jihadist group conquered swaths of Iraq in 2014.

Flourishing in the ruins of post-Qaddafi Libya, the Islamic State has grown ambitious enough to attack neighboring Tunisia. Meanwhile, the Pentagon has drawn up plans for U.S. military operations, including airstrikes against up to 40 targets.